The objective of this research is to further our understanding of gamma-tubulin biogenesis and function and to increase our understanding of microtubule organizing center (MTOC) and spindle structure and function, using the microtubule cytoskeleton of the budding yeast, S. cerevisiae as a model system. Gamma-tubulin, a conserved component of MTOCs and an intrinsic component of the yeast MTOC, the spindle pole body (SPB), plays an essential role in the formation of a functional bipolar mitotic spindle. Accurate chromosome segregation during cell division is dependent upon proper functioning of the mitotic spindle. Defects in chromosome segregation can result in aneuploidy, a deviation in the normal chromosome number, which is one of the genetic changes often found in tumor cells. In an effort to increase our understanding of processes requiring gamma-tubulin and/or microtubule function, genetic and biochemical approaches will be used to analyze several proteins that are implicated in cellular processes involving gamma-tubulin and/or microtubules in yeast. Gamma-tubulin is an important component of the SPB and appears to be intimately involved in MTOC function and spindle organization; therefore, a more comprehensive understanding of gamma-tubulin, and proteins associated with gamma-tubulin, may provide insights regarding the structure and function of the MTOC as well as microtubule function and dynamics. Given the functional similarity between MTOCs from yeast and higher eukaryotes, and the universality of gamma-tubulin, information obtained from the study of the SPB and gamma-tubulin in yeast will likely be applicable to mammalian cells. In fact, two proteins that have been shown to interact with gamma-tubulin in yeast, Spc97p and Spc98p, have homologues in the human genome.